The present invention relates to an off cycle damper system for a furnace and more particularly to a furnace having damper means adjacent an inlet opening to a burner means and heat exchanger means associated therewith for closing the inlet opening when the burner means is off, and when said damper means is open to a predetermined position, said burner means may be ignited.
It is known in the art to provide an automatic damper in an exhaust conduit or flue conduit leading from a furnace combustion chamber and heat exchanger associated therewith to the atmosphere. When the damper is closed, the operation of the fuel feeding device will be stopped. The damper may be opened by a motor and closed by gravity. A control is provided to prevent the supply of fuel when the damper is closed. One patent exemplifying such prior art device is Lencke et al. 2,085,912.
Other patents are known which describe control systems for controlling a flue damper in a furnace flue. See, for example, Zivny 4,416,611, Clouser 4,570,847; and Grant 4,619,602. Also, it is known from Butzen 4,421,096, for example, to provide a flue damper having a motor for driving the damper closed and a spring for biasing the damper open.
The prior art recognizes the need to increase furnace efficiency, whether the furnace be gas or oil fired. Generally, the flue is closed a short time after combustion is terminated. It is recognized that positioning the damper in the flue created problems, such as relatively high temperatures in the environment of the damper and its controls. On occasion the hostile environment caused breakdown of components and operational and maintenance problems. Prior designs incorporating springs or bimetal elements to open or close the damper have been subject to mechanical fatigue.
An object of the present invention is to provide a damper means for a furnace which is positioned adjacent the inlet to the burner means whereby the disadvantages and deficiencies of certain prior damper constructions are obviated.
Another object of the present invention is to provide a damper means for a furnace that is operable to control the flow of air to the heat exchanger, said damper means being closed when the burner means is off and being open when the burner means is on.
Yet another object of the present invention is to provide a furnace with improved damper means for conserving energy during the off cycle of the burner, said damper means being located adjacent an inlet opening to the burner means and heat exchanger for controlling the passage of air through said inlet opening, and said damper means not being disposed in the flue gas environment.
A further object of the present invention is to provide a furance with novel damper means adjacent the inlet to the burner means, said damper means comprising a plate member having a small opening therein for permitting a small quantity of air to reach the burner means when the plate member is closed for supporting a pilot flame.
Other objects and advantages of the present invention will be made more apparent hereinafter.